I. Field of Use
The present application relates to the field of home security. More specifically, the present application relates to door and window sensors typically used in homes and businesses.
II. Description of the Related Art
Security systems for homes and businesses have been around for many years. Often, these systems make use of sensors installed onto doors and windows to determine whether the doors or windows are in an open or closed state using a magnet and a reed switch in combination with each other. The magnet is typically installed onto a movable part of a window or onto a door, while the detector is mounted to a stationary surface, such as a door or window frame. When the door or window is closed, the magnet and reed switch are in close proximity to one another, maintaining the reed switch in a first state indicative of a “no alarm”, or “closed”, condition. If the door or window is opened, proximity is lost between the magnet and the reed switch, resulting in the reed switch changing state, e.g., from closed to open or from open to closed. The change of state is indicative of an alarm condition, and a signal may be generated by circuitry associated with the reed switch and sent, via wires or over-the-air, to a central processing station, either in the home or at a remote monitoring facility. Alternatively, or in addition, a loud audible alert may be generated, either at the central processing station in the home or directly by the circuitry associated with the reed switch, indicating that a door or window has been opened (or closed).
More recently, advances in technology allow door and window sensors to determine more than just the open or closed status of a door or window. For example, U.S. patent application Ser. No. 12/323,542, assigned to Andersen Corporation of Bayport, Minn., describes a window sensor apparatus that is able to determine both an open or close status of a window and a locked or unlocked status of a window lock associated with the window. The apparatus uses a first sensor to determine whether the window is closed or open, and a second sensor to determine whether a locking mechanism associated with the window is in a locked or unlocked state. Each of the sensors provides information to a processor, where it may be then transmitted to a remote monitoring device, such as a central alarm system.
One of the disadvantages of the prior art described above is that it requires two, independent sensors, thus allowing for two potential points of failure in the system.
Another disadvantage of the prior art is the cost and complexity of using two, independent sensors. While having two sensors allows the apparatus to determine two, independent statuses of the window (i.e., open/closed and locked/unlocked), the cost of such a device must reflect the use of both sensors. Additionally, the complexity of the design is increased due to the required physical placement of the second sensor in a limited area, such as in the window lock and/or window frame.
Thus, it would be desirable to provide a security sensor that eliminates the shortcomings of the prior art.